I don't know why I kept missing this when I was reading Plotinus, but I am glad I have finally found a url that spelled it out to me in easy-to-understand layman English.
I believed that the ancient Neo-Platonists must have had a concept for an astral-body as it were, but I couldn't find it in the writing of Plotinus. It was there though. Its called Pneuma! Duh.
The soul(Psyche) forms a luminous body around it called the Pneuma, and as it descends down through the celestial world it becomes heavier and more material. By the time it passes the lunar sphere it is heavy enough to attach to the physical body(Soma) of the earthy domain.
Thanks to :
http://www.societasviaromana.net/Collegium_Religionis/animamystery.php in his wrinting.
My assumptions at this point:
I assume that this attachment of Pneuma to the physical body(Soma) probably occurs at the first breath of the infant. And the aura is infact the spiritual light of the resident Pneuma.